网络通信

网络上寻找主机

import socket
print socket.gethostname()

使用gethostbyname()访问操作系统主机名解析API，将服务器名字转换为其数字地址。

import socket

for host in ['homer','www','www.python.org','nosuchname']:
    try:
        print "%s:%s" % (host,socket.gethostbyname(host))
    except socket.error, msg:
        print "%s:%s" % (host,msg)

　　

使用gethostbyname_ex()，返回服务器的标准主机名/所有别名/以及所有ip地址。

import socket

for host in ['homer','www','www.python.org','nosuchname']:
    print host
    try:
        hostname,aliases,addresses = socket.gethostbyname_ex(host)
        print 'hostname:',hostname
        print 'aliases:',aliases
        print 'addresses:',addresses
    except socket.error as msg:
        print 'ERROR:',msg
    print

　　

如果得到一个服务器地址，通过gethostbyaddr()可以用来逆向查找得到主机名。（只有本地可行...why）

import socket

hostname,aliases,addresses = socket.gethostbyaddr('192.168.0.100')

print 'Hostname:',hostname
print 'Aliases:',aliases
print 'Addresses:',addresses

　　

通过getservbyname()查找服务信息/端口

import socket
from urlparse import urlparse

for url in ['http://www.python.org',
            'https://www.mybank.com',
            'ftp://prep.ai.mit.edu',
            'gopher://gopher.micro.umn.edu',
            'smtp://mail.example.com',
            'imap://mail.example.com',
            'imaps://mail.example.com',
            'pop3://pop.example.com',
            'pop3s://pop.example.com',
            ]:
    parsed_url = urlparse(url)
    port = socket.getservbyname(parsed_url.scheme)
    print '%s:%s' % (parsed_url,port)

　　

通过getservbyport()逆向查找端口(匹配法)。

可以使用gtprotobyname()获取分配给一个传输协议的端口号。

查找服务器地址

getaddrinfo()将基本地址转换为一个元组列表，其中包含建立一个连接所需的全部信息。

import socket

def get_constants(prefix):
    return dict(
        (getattr(socket,n),n)
        for n in dir(socket)
        if n.startswith(prefix)
    )

families = get_constants('AF_')
types = get_constants('SOCK_')
protocols = get_constants('IPPROTO_')

for response in socket.getaddrinfo('www.python.org','http'):
    family,socktype,proto,canonname,sockaddr = response

    print 'Family:',families[family]
    print 'Type:',types[socktype]
    print 'Protocol:',protocols[proto]
    print 'Canonical name:',canonname
    print 'Socket Address',sockaddr
    print

　　

TCP/IP服务端和客户端

服务端：创建套接字->bind()->listen()->accept()

客户端：创建套接字->connect()->sendall()

服务端

import socket
import sys

#创建一个套接字
sock = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
#bind()将套接字与服务器地址关联
server_address = ('localhost',9999)
print >>sys.stderr,'starting up om %s port %s' % server_address
sock.bind(server_address)
#调用listen()将套接字置为服务器模式，调用accept()等待到来的连接
sock.listen(1)

while True:
    print >> sys.stderr,'waiting for a connection.'
    connection,client_address = sock.accept()
    #xxx
    try:
        print >>sys.stderr,'connection from',client_address

        while True:
            data = connection.recv(16)
            print >>sys.stderr,'received "%s"' % data
            if data:
                print >>sys.stderr,'sending data back to the client'
                connection.sendall(data)
            else:
                print >>sys.stderr,'no data  from',client_address
                break
    finally:
        connection.close()

客户端

import socket
import sys

#创建一个TCP/IP套接字
sock = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
#连接这个套接字到正在等待回应的服务器
server_address = ('localhost',9999)
print >>sys.stderr,'connecttin to %s port %s' % server_address
sock.connect(server_address)

#连接上后，传输数据
try:
    #传送数据
    message = 'there is p0pl4r,who are u?'
    print >>sys.stderr,'sending %s' % message
    sock.sendall(message)

    #等待回应
    amount_received = 0
    amount_expected = len(message)

    while amount_received < amount_expected:
        data = sock.recv(16)
        amount_received += len(data)
        print >>sys.stderr,'received "%s"' % data

finally:
    print >>sys.stderr,'closing socket.byebye'
    sock.close()

使用Python搭建HTTP PUT服务器

代码以下保存到HTTPutServer.py文件里：

# ref: https://www.snip2code.com/Snippet/905666/Python-HTTP-PUT-test-server
import sys
import signal
from threading import Thread
from BaseHTTPServer import HTTPServer, BaseHTTPRequestHandler



class PUTHandler(BaseHTTPRequestHandler):
    def do_PUT(self):
        length = int(self.headers['Content-Length'])
        content = self.rfile.read(length)
        self.send_response(200)
        with open(self.path[1:], "w") as f:
            f.write(content)


def run_on(port):
    print("Starting a HTTP PUT Server on {0} port {1} (http://{0}:{1}) ...".format(sys.argv[1], port))
    server_address = (sys.argv[1], port)
    httpd = HTTPServer(server_address, PUTHandler)
    httpd.serve_forever()


if __name__ == "__main__":
    if len(sys.argv) < 3:
        print("Usage:
	python {0} ip 1337".format(sys.argv[0]))
        sys.exit(1)
    ports = [int(arg) for arg in sys.argv[2:]]
    try:
        for port_number in ports:
            server = Thread(target=run_on, args=[port_number])
            server.daemon = True # Do not make us wait for you to exit
        server.start()
        signal.pause() # Wait for interrupt signal, e.g. KeyboardInterrupt
    except KeyboardInterrupt:
        print "
Python HTTP PUT Server Stoped."
        sys.exit(1)
运行方法：

$ python HTTPutServer.py 10.10.10.100 1337
Starting a HTTP PUT Server on 10.10.10.100 port 1337 (http://10.10.10.100:1337) ...